This disclosure relates generally to the field of image processing. More particularly, but not by way of limitation, this disclosure relates to a technique for addressing the issue of residual noise (in the form of a black-level offset) in an image capture system.
Many electronic devices include image capture units. Common to these units is the use of a light-capturing sensor that can generate frames of raw image data (e.g., CMOS or CCD). These frames are processed before being stored in memory and/or displayed. For efficiency, many of these electronic devices process raw image data through a dedicated image processing pipeline, referred to herein as an image signal processor (ISP). Capturing images in low-light conditions presents a number of challenges for such systems for, despite advancements in noise reduction, the image signal output from a sensor will contain residual noise; noise that will be amplified as the image signal passes through the ISP.